By CNN Senior International Correspondent Nic Robertson and Paul Cruickshank

Editor's note: This story is based on interrogation reports that form part of the prosecution case in the forthcoming trial of six Belgian citizens charged with participation in a terrorist group. Versions of those documents were obtained by CNN from the defense attorney of one of those suspects. The statement by Bryant Vinas was compiled from an interview he gave Belgian prosecutors in March 2009 in New York, and was confirmed by U.S. prosecutors as authentic. The statement by Walid Othmani was given to French investigators, and was authenticated by Belgian prosecutors.

A photo purporting to show Moez Garsallaoui firing a rocket launcher on the Afghanistan-Pakistan border.

(CNN) -- When Bryant Neal Vinas spoke at length with Belgian prosecutors last March, he provided a fascinating and sometimes frightening insight into al Qaeda's training -- and its agenda.

Vinas is a young American who was arrested in Pakistan late in 2008 after allegedly training with al Qaeda in the Afghan/Pakistan border area.

He was repatriated to the United States and in January pled guilty to charges of conspiracy to murder U.S. nationals, providing material support to a foreign terrorist organization, and receiving military-type training from a foreign terrorist organization.

In notes made by FBI agents of interviews with Vinas, he admits he went to Pakistan to join al Qaeda and kill U.S. troops in Afghanistan. But the terror group appeared to have other ideas for him. He volunteered to become a suicide bomber but was dissuaded at every turn. On Thanksgiving weekend last year, shortly after his arrest, much of the New York mass transit system was put on high alert, including Penn Station. According to the Belgian prosecutor's document, Vinas had told al Qaeda's command everything he knew about the system.

Vinas's account of his time in al Qaeda training camps in Pakistan is a playbook of how the terror group survived after 9/11 and continues to operate in the remote hills of Pakistan.

Al Qaeda has shown remarkable adaptability and remains as committed as ever to launching attacks in the West, according to the descriptions of several alleged Western recruits, including Vinas, who spent time together in al Qaeda camps in the region between September 2007 and December 2008.

In their interrogations, the recruits revealed al Qaeda's continued determination to attack mass transport systems in the West and training programs for new forms of attack, including breaking into residences to carry out targeted assassinations.

The documents provide an inside view of al Qaeda's organizational structures, training programs, and the protective measures the terrorist organization has taken against increasingly effective U.S. missile strikes.

And they arguably shed more light on the state of al Qaeda than any previously released into the public domain.

Intelligence officials say intensified U.S. Predator drone strikes have degraded al Qaeda's capabilities since the end of last year, but the accounts suggest that because of the decentralization of its organization and close ties with the Pakistani Taliban, the terrorist network will be difficult to dislodge from Pakistan's tribal areas.

Despite not being able to operate training camps on anything like the scale they did in Afghanistan, the accounts suggest that al Qaeda has been able to sustain many of its training operations by confining them to small dwellings in the remote mountains of Waziristan. Inside these dwellings bomb-making training appears to have been emphasized, some of it very sophisticated.

An American joins al Qaeda

On September 10, 2007, almost exactly six years after al Qaeda attacked New York, Vinas, a 24-year-old Queens-born American citizen boarded a flight from the city en route to Lahore, in eastern Pakistan, determined to fight jihad in neighboring Afghanistan.

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Brought up a Catholic by his Latin American immigrant parents, who divorced when he was young, Vinas tried to join the U.S. army in 2002 but dropped out after just a few weeks.

In 2004 -- for reasons which are still unclear -- he converted to Islam and started frequenting a mosque in Long Island near where he lived with his father. Over the next three years he became radicalized, U.S. officials have stated, in no small part because of his exposure to pro-al Qaeda Web sites.

A former U.S. government official told CNN that youths influenced by the ideas of the British pro-al Qaeda extremist group Al Muhajiroun were known to have hung out in the vicinity of the mosque at the same time as Vinas.

The former official told CNN that they were a splinter group of the Al Muhajiroun followers who used to hang out in the New York/Long Island area in the late 1990s and early 2000s.

Al Muhajiroun's American members, the former official stated, included Syed Hashmi, a Brooklyn college graduate who traveled to Pakistan in 2003 and now awaits trial on charges of providing material support to the terrorist network. He has pled not guilty.

Another who belonged to Al Muhajiroun was Mohammed Junaid Babar, a trainee Queens taxi driver, who met two of the July 7, 2005 London bombers in Pakistan and who in 2004 pled guilty to providing material support to terrorists in Pakistan. Al Muhajiroun was formally disbanded in October 2004 but still operates, CNN has discovered, under a variety of guises.

Anjem Choudhary, the former deputy leader of Al Muhajiroun, told CNN Monday that New York was one of the organization's main hubs before 2004. He says dozens of followers from the New York area still regularly tune into online sermons put together by the group's founder Omar Bakri Mohammed in Tripoli, Lebanon, where he has been living since being banned from the UK after the 2005 London bombings.

Choudhary stated that he and Bakri were still loosely affiliated with The Islamic Thinkers Society, a New York based organization, which says the peaceful restoration of the Islamic Caliphate is one of its objectives.

A March 5, 2009 posting on the homepage of its Web site states that Bakri Mohammed is "a man who has inspired thousands across the world to rise for Islam." The Islamic Thinkers Society exists legally in the United States and says it is committed solely to the political and intellectual struggle for Islam.

When Vinas arrived in Lahore he had little idea about how he was going to gain access to the fighting in Afghanistan, according to his own account. But a few days after he arrived he sought help from a New York friend whom he knew moved in militant circles.

One introduction led to another and eventually Vinas met a Jihadist commander about to return to Afghanistan. Identified in legal documents as S.S., their commander agreed to let him join his group. CNN has learned from a source briefed on the case that the initials S.S. stand for a man who goes by the name of Shah Saab, and is believed to be somewhere in Pakistan's tribal areas.

At the end of September Vinas was whisked in the commander's car into Pakistan's tribal areas and then across the border into Afghanistan to join up with a small band of fighters targeting an American base. The raid however was called off at the last minute because of American aircraft circling above.

His quick introduction to the fighting appears to have been unusual. Vinas stated it was standard for fighters to undergo military training before being selected for such missions.

It is possible he persuaded his handlers that his brief stint as a U.S. army recruit justified him being fast-tracked; or perhaps the jihadist group just needed more fighters.

On his return to Mohmand, a district in Pakistan's tribal areas, Vinas was asked by one of the fighters if he wanted to become a suicide bomber. Vinas, according to his own account, accepted and was sent to Peshawar, Pakistan, for more instruction.

But his handlers there judged that he had not received enough religious instruction to launch such an attack. Perhaps it was dawning on them just how valuable an American recruit might one day be.

Vinas stated that at this point he traveled back to a village in Waziristan where he spent time with a number of al Qaeda members, including a number of Saudis and Yemenis.

In March 2008 he successfully persuaded one of them, a Yemeni he identified as Soufran, to recommend him for formal membership in the terrorist group. Only Soufran's initials appeared in the legal document but CNN obtained his name from a source briefed on the case. His current whereabouts are unknown.

According to Vinas, al Qaeda recruits were asked to fill out forms with personal information and hand over their passports when they joined the organization, but were not required to sign a contract or take part in a ceremony to become a member of al Qaeda.

The Belgian-French group

Around this time, Vinas says in his interrogation, he came across several Belgian and French militants who had traveled to Pakistan's tribal areas at the beginning of the year, also intent on fighting in Afghanistan.

The group's members -- four Belgians and two French citizens, all of North African descent -- were recruited, Belgian police say, by Malika el Aroud and Moez Garsallaoui, a married couple who had long enjoyed a notorious reputation among European counter-terrorism services.

El Aroud's previous husband, Abdessattar Dahmane, had assassinated Ahmed Shah Massoud, the head of the anti-Taliban Northern Alliance, in a suicide bombing attack ordered by Osama bin Laden two days before 9/11.

When CNN interviewed the couple in 2006, El Aroud showed how she administered a pro-al Qaeda Web forum called Minbar SOS, which included pro-al Qaeda postings and propaganda videos.

Belgian investigators say the Web site played an important role in the radicalization of members of the French-Belgian group.

One of them was a 25-year-old Frenchman, Walid Othmani. He was arrested on his return to France from Pakistan. Belgian prosecutors told CNN Othmani has been charged in France with participation in a criminal conspiracy with the aim of preparing a terrorist act.

"I don't think I would have left to fight Jihad without viewing these videos [on Minbar] ... it made me aware that the European media were hiding things about the situation in Palestine, Iraq and Afghanistan," Othmani told French interrogators, according to Belgian legal documents obtained by CNN.

According to Belgian counter-terrorism officials, Garsallaoui, a Tunisian citizen, recruited some of those who traveled to Pakistan in person in Brussels, but relied on the Internet to recruit others.

The six recruits met Garsallaoui in Istanbul in December 2007. With Garsallaoui setting off first, they followed him towards Pakistan, paying off a series of people-smugglers between Turkey, Iran and Pakistan, to gain entry to al Qaeda's heartlands in the mountains of Waziristan.

Vinas says he met with at least three members of this group in Waziristan: its leader Moez Garsallaoui, Hamza el Alami, and Hicham Bouhali Zrioul, a Belgian-Moroccan who once worked as a taxi driver in Brussels. All three are believed by Belgian intelligence officials to be at large in the mountainous area along the Pakistan/Afghan border.

Three other members -- Hicham Beyayo, Ali El Ghanouti and Said Harrizi -- were arrested when they returned to Belgium and have been charged with participation in a terrorist group. They don't dispute they went to fight Jihad; they do deny participating in a terrorist group.

Al Qaeda's new training facilities

Between March and July 2008 Vinas stated that he attended three al Qaeda training courses, which focused on weapons, explosives, and rocket-based or propelled weaponry.

During these classes, attended by 10-20 recruits, Vinas was taught how to handle a large variety of weapons and explosives, some of them of military grade sophistication, according to his account.

Vinas stated he became familiar with seeing, smelling and touching different explosives such as TNT, as well as plastic explosives such as RDX, and Semtex, C3 and C4 -- the explosive U.S. authorities have stated was used in al Qaeda's attack on the USS Cole in 2000. Vinas also learned how to make vests for suicide bombers.

Vinas stated that he was also instructed how to prepare and place fuses, how to test batteries, how to use voltmeters and how to build circuitry for a bomb. According to his account, al Qaeda also offered a wide variety of other courses including electronics, sniper, and poisons training.

Instruction in the actual construction of bombs, he stated, was offered to al Qaeda recruits who had become more advanced in their training.

Vinas' training during this period was very similar to the training described by members of the French-Belgian group. Othmani, the French recruit, stated that the group were given explosives training and taught how to fire rocket launchers and RPGs.

Like Vinas, the group had been required to sign forms before their training. Othmani stated that his group was required to pledge absolute obedience to their handlers and indicate whether they wanted to become suicide bombers.

Othmani provided interesting new details about the training facilities being used by al Qaeda in the tribal areas.

His group trained in a small mountain shack, a far cry from the large camps al Qaeda had run in Taliban-era Afghanistan, when it had been able to operate with little danger of being targeted by military strikes.

However the wide number of training courses described by both Vinas and Othmani suggest that al Qaeda has been able to adapt well to the new security environment. By operating a larger number of smaller facilities, al Qaeda would also appear to have increased its resilience to attack.

While the classrooms are safer from drone attacks than the pre-9/11 sessions on the mountainsides the content seems to have changed to match new targeting plans.

Suicide vest and IED construction show how the curriculum is being modified for today's combat with U.S. troops in Afghanistan. Making and handling explosives, as well as fuse construction, show the sessions may also be geared for killing in Europe and the United States.

These are the very skills the July 7, 2005 London bombers Shehzad Tanweer and Mohammed Siddique came to Pakistan to learn. Al Qaeda, it would seem, may still want to pull off spectacular attacks in Europe or the United States.

Vinas says he took a course in propelled weaponry with Zrioul, the former Brussels taxi driver, whom he first met in March 2008, and formed a friendship with.

Vinas stated that when they completed their training, al Qaeda instructors did a written evaluation of their performance. Vinas had been judged qualified to participate in missile attacks against U.S. and NATO bases in Afghanistan, according to his account.

That suggests al Qaeda has maintained its capacity for administration and paperwork even in a harsher security environment.

When their training finished in the summer of 2008, Vinas and Zrioul lived in the same house in the mountains of Waziristan. Zrioul managed to acquire a computer which he rigged up to watch Jihadist videos.

According to Othmani, al Qaeda fighters numbered between 300-500 in Pakistan's Tribal Areas -- spread out in groups of 10. Such decentralization was a function of the growing deadliness of U.S. military strikes using Predator drones.

Hicham Beyayo, one of the Belgian Jihadist volunteers, said his group moved around a lot because such strikes were known to be "very effective," his lawyer, Christophe Marchand told CNN.

The loss of an increasing number of operatives, stated Othmani, prompted an order from al Qaeda's top command for fighters to remain inside as much as possible. In order to keep in touch jihadists operated a courier service across the region according to the Frenchman's testimony.

The decentralization of al Qaeda's structures appear to have created some costs for recruits.

Two members of the Belgian-French group describe feeling increasingly cut off, bored, and fed up with the primitive living conditions in their mountain shacks.

They often did not seem to know what their next orders would be or where their handlers would take them. They also described being deeply frustrated at being repeatedly given false promises that they would be able to fight in Afghanistan.

Othmani also described the group's frustration at having to pay for their own weapons and training -- at a cost of €1,300 (about $1,800) -- which if true might lend credence to reports that al Qaeda has come under financial strain. Vinas, for his part, made no mention of having to make payments to his handlers.

New attack plans

During a mountain walk with Zrioul one day, Vinas says he was told about a new course being taught by al Qaeda called "international operations" set up by the organization's head of international operations whom Vinas later identified as Abu Hafith.

Hafith, he stated, was responsible for recruitment and direction of terrorist cells, and attacks outside Pakistan and Afghanistan. Hafith was identified by his initials in the legal document but CNN obtained his name from a source briefed on the case. He is believed to be still at large in the Pakistan-Afghan border area.

Vinas was told that the training course Hafith set up focused on kidnapping and assassination, including instruction on the use of silencers and how to break into and enter a property.

The revelations raise the possibility that al Qaeda was developing a program of targeted assassinations. Though al Qaeda has carried out some assassinations in the past, most of its attacks in the West have not targeted any particular individuals but crowded areas, such as mass transport.

Vinas stated that Zrioul also discussed with him an attack on the Brussels metro, telling him it was a soft target because it was poorly protected. He said Zrioul also raised the possibility of launching an attack on a European football stadium.

A senior Belgian intelligence official told CNN that Belgian security services only learned about these conversations in March 2009 after Vinas met with Belgian prosecutors in New York. Although concerned, Belgium's intelligence service concluded that no concrete plot had likely existed, said the official.

Such conversations illustrate the terror network's continued desire to inflict mass casualties. Vinas stated that he himself gave detailed briefings to al Qaeda chiefs in Waziristan in September 2008 about how the Long Island Commuter Rail service worked, according to a federal indictment earlier this month.

Vinas' life as an al Qaeda fighter saw him rotate between fighting behind enemy lines in Afghanistan, training in remote mountain dwellings in the tribal areas, and spending downtime in Peshawar, the capital of Pakistan's North West Frontier Province, movements which indicate that al Qaeda has recently found it possible to operate in a large swath of territory across Pakistan's North-west.

Vinas not only had a toe amputated in Peshawar, but also went there to look for a wife. None of this would have happened without al Qaeda's blessing. Although he was ultimately arrested in Peshawar, al Qaeda would not have signed off on his visits unless they'd felt confident he'd be safe there.

Meetings with top al Qaeda leaders

During his travels Vinas met some of al Qaeda's top leaders, leaders he was able to identify to U.S. authorities after his capture. According to U.S. investigators, quoted by the Los Angeles Times, Vinas says he met with Abu Yayha al Libi, one of al Qaeda's principal spokesmen and Rashid Rauf, the British al Qaeda operative suspected of coordinating a plot against transatlantic aviation in August 2006. Rauf, who was arrested that August in Pakistan, escaped from custody in December 2007 but is believed to have been killed in a Predator strike in North Waziristan in November 2008.

Vinas says he also met with an individual by the name of Abdullah Saeed, whom he says replaced Abu Leith al Libbi as al Qaeda's military chief in Afghanistan and Pakistan in January 2008. A former jihadist told CNN that Saeed is almost certainly Mustafa Abu Al-Yazid, an Egyptian also known as Sheikh Saeed. In June Al-Yazid released an audio recording complaining of a lack of funds for the fighting in Afghanistan.

Raids into Afghanistan

Vinas stated that he met with Saeed in the late summer of 2008 in Waziristan, and al Qaeda's military chief personally instructed him to join a group of fighters targeting American bases from the tribal areas of Pakistan. This January, Vinas pleaded guilty to having targeted an American base in September 2008.

That attack however appears to have been a failure. Creeping up towards the American forward operating base Vinas and other al Qaeda fighters' first attempt to fire on the base was botched by radio problems. The second rocket attack fell short of the base, according to Vinas' account.

Attacks by his associates however may have been more deadly. In June 2008 Moez Garsallaoui, the French-Belgian group leader, wrote an email to his wife in Belgium, intercepted by U.S. counter-terrorism agencies, in which he claimed to have killed several Americans in Afghanistan, according to Belgian legal documents.

And Walid Othmani said that in July 2008 Garsallaoui told him he had killed Americans by firing rockets at an American combat outpost from Pakistan, according to the documents. As he was not specific about the date, CNN has not been able to substantiate the claim.

Both Vinas and Othmani described close ties between al Qaeda and Taliban elements in the tribal areas of Pakistan.

The relationship between the two groups was so close, Vinas stated, that members of al Qaeda were also sometimes simultaneously members of the Taliban.

Garsallaoui appears to be one such recruit. In a message he posted on Minbar SOS on May 11, 2009, discovered by CNN, he described undertaking raids with "brother Taliban" from the tribal areas of Pakistan against targets in Afghanistan. "Nothing has given me greater pleasure than encountering [American] soldiers during long days on the battlefield," he said.

A continued threat to the West.

Between late July and early December of 2008 four members of the Belgian-French group -- Beyayo, El Ghanouti, Harrizi and Othmani -- returned to Europe.

On December 11 Belgian counter-terrorism police launched one of the largest operations in the country's history, arresting six people including Garsallaoui's wife Malika el Aroud and charging them with participation in a terrorist group.

According to Belgian counter-terrorism sources, the trigger for the Brussels arrests was an intercepted e-mail sent by one of the alleged recruits, Beyayo, in early December shortly after he returned to Belgium.

The e-mail allegedly suggested Beyayo had been given the green light to launch an attack in Belgium.

However no explosives were recovered by Belgian police, and some terrorism analysts are skeptical that an attack was imminent.

Beyayo's lawyer, Christophe Marchand, told CNN in February that the e-mail was merely "tough talk" to impress an ex-girlfriend. Belgian authorities continue to insist that the alleged cell was a potential national security threat.

Vinas, for his part, was arrested by Pakistani police in Peshawar in November 2008 and transferred into American custody.

Of those still thought to be at large, Garsallaoui issued this threat to Belgium authorities on his wife's Web site on May 11, 2009: "If you thought that you could pressure me to slow down through the arrest of my wife, you were wrong. It won't stop me fulfilling my objectives... the place of my wife in my heart and the heart of all the mujahedeen is greater than ever... Surprises are sure to be in store for you in the days ahead. Those who laugh last, laugh more."

Such threats will have caused concern because of Garsallaoui's wide connections in European militant circles. Two of his Brussels associates, Bassam Ayachi, 62, and Raphael Gendron 33, are in custody in Italy, charged with being leaders of a logistical support team for al Qaeda. They have denied the charges.

The duo, who were detained in the port city of Bari in November for trying to illegally smuggle Middle Easterners into the country, had allegedly talked to each other in their detention center about what sounded like a scheme to attack Charles de Gaulle airport in Paris, a conversation bugged by Italian police. French officials have said they were never aware of a concrete plot to attack the airport.

According to a senior Belgian intelligence official, Garsallaoui, his wife El Aroud, and several others who traveled to Pakistan were all connected through the Centre Islamique Belge, an organization Belgian authorities say espouses hardline Salafist and pro-al Qaeda views.

In past interviews the organization's founder Bassam Ayachi has said it concentrates on pastoral care for Muslims in Brussels and did not promote pro-al Qaeda views.

Members of the Brussels-based group are believed to have received terrorist training in other countries besides Pakistan.

In late May, several days before U.S. President Barack Obama traveled to Cairo to give a major speech, several Belgian citizens were arrested in Egypt and accused of being members of a terrorist cell affiliated with al Qaeda.

A senior Belgian counter-terrorism official told CNN that two Belgians now in Egyptian custody were known associates of Garsallaoui at the Centre Islamique Belge and are believed to have received military training with an ultra-extremist Palestinian group in Gaza.

"Anybody who gets such training is obviously a potential danger if they return to Europe," said the official.

The insider accounts of al Qaeda operations in the tribal areas of Pakistan make clear the terrorist organization's continued determination to attack the West.

While the potential pool of recruits may have shrunk significantly because of a backlash against al Qaeda in Muslim communities around the world -- due to its targeting of civilians and the fact that so many of its victims have been Muslim -- the insider accounts suggest that there are still a significant number of hardcore extremists in the West and in Muslim countries -- who are willing to join bin Laden's terrorist outfit.

The insider descriptions provided by Vinas and Othmani indicate that these violent extremists are as motivated as any of their predecessors.

Their accounts also indicate that the al Qaeda network has demonstrated a remarkable ability to adapt its operations to a much harsher security environment.

But Vinas and Othmani's accounts also suggest that al Qaeda may be having leadership problems.

While able to find fresh recruits to replace those killed and arrested it seems to have more difficulty replacing senior military trainers and other key operational figures.

A former U.S. government official, specializing in counter-terrorism, commented that the insider accounts suggest the same people are leading training as a decade ago.

The only difference, there are fewer of them. Perhaps those killed or captured along the Afghan/Pakistan border are not being replaced.

Recent reports that al Qaeda is moving some operatives out of the tribal areas of Pakistan towards safer placements in Pakistani cities, or to Jihadist fronts in other countries such as Yemen and Somalia, may indicate that the pressure from U.S. missile strikes is starting to show.

But the decentralization of al Qaeda's training and their ever closer ties with local Pakistani Taliban, mean it remains extremely difficult to eliminate from the mountains between Afghanistan and Pakistan.

Above all the accounts from Vinas and others show that al Qaeda's training structures have but one goal, another 9/11.